Persons involved in the development of point of purchase advertising display devices are primarily concerned with the problem of continuing to develop new devices which provide attractive and eye-catching visual effects. Many point of purchase advertising display devices utilize a light box with two or more relatively shiftable parallel panels having patterns of light transmitting spots or holes which may provide a shifting visual effect by moving one of the panels relative to the other so that the transparent spots of one panel are moved in and out of register with the spots of the other panel.
Devices of the above described type may have random patterns of transparent spots which serve to catch the eye and thus bring attention to a fixed advertising message. Others combine such random spots with spots which are arranged to define alpha-numeric characters so that an advertising message may be visible during a part of each cycle of the movable panel.
Many patents have issued upon devices of the foregoing general type, and a typical U.S. Pat. No. is 1,172,360.